1. Field of the Invention
The present invention relates to a stereoscopic image display device using a liquid crystal barrier panel (LC barrier-panel). In particular, the present invention relates to a stereoscopic image display device capable of stereoscopic view in both portrait and landscape screens by rotating a display panel together with the LC barrier-panel.
2. Description of the Related Art
As stereoscopic image display systems, there are an auto-stereoscopic image display system and a glasses stereoscopic system. As the glasses stereoscopic system, a head mount display system and a system using polarized glasses are commercialized. However, it is inconvenient to wear glasses or the like to view a display image on a mobile device. The auto-stereoscopic image display system does not have such inconvenience and is suitable for a display device of mobile use.
As the auto-stereoscopic image display system, a parallax barrier system is known. The parallax barrier system uses a barrier panel disposed on the front or back surface of a display panel. A left image and a right image are displayed on vertical pixel columns (vertical lines) every other line alternately on the display panel. For instance, the right image for the right eye is displayed on odd-numbered vertical lines while the left image for the left eye is displayed on even-numbered vertical lines. The barrier panel is a shading mask of a vertical stripe having substantially the same pitch as the vertical lines of the display panel. When the observer sees the display panel through the barrier panel, the right eye can see the odd-numbered vertical lines but cannot see the even-numbered vertical lines that are blocked by the barrier panel. The left eye can see the even-numbered vertical lines but cannot see the odd-numbered vertical lines that are blocked by the barrier panel. Therefore, the observer can see the left and right images on the display panel simultaneously by naked eyes so as to recognize a stereoscopic image.
In recent mobile devices, the display panel can be rotated to view both portrait and landscape images. However, the barrier panel is fixed to the display panel in the parallax barrier system, and hence, when the display panel is rotated, the vertical stripe of the barrier panel is also rotated to be a horizontal stripe. As a result, the stereoscopic image utilizing parallax between left and right images cannot be observed. Therefore, Japanese Patent Application Laid-open No. 2006-243710 (hereinafter, referred to as Patent Document 1) proposes a barrier liquid crystal panel (LC barrier panel) that can switch between vertical and horizontal stripes so as to display the vertical stripe even if the display panel is rotated.
FIG. 10 is a cross-sectional view of a LC barrier panel 90 disclosed in Patent Document 1. Liquid crystal 93 is filled in between a first substrate 91 and a second substrate 92. FIGS. 11A and 11B schematically illustrate shapes of electrodes formed on inner surfaces (facing the liquid crystal 93) of the first substrate and the second substrate, respectively. As illustrated in FIG. 11A, on the first substrate 91, first electrodes 94 and second electrodes 96 having a band-like shape elongated in an x direction are formed so as to engage each other. In addition, the plurality of first electrodes 94 are electrically connected by a first connection electrode 95. Those are referred to as a first electrode set 81. Similarly, the plurality of second electrodes 96 are electrically connected by a second connection electrode 96. Those are referred to as a second electrode set 82. Therefore, the electrodes of the first electrode set 81 and the second electrode set 82 have a comb-like shape. On the other hand, as illustrated in FIG. 11B, on the second substrate 92, third electrodes 98 and fourth electrodes 99 having a band-like shape elongated in a y direction are formed so as to engage each other. In addition, the plurality of third electrodes 98 are electrically connected by a third connection electrode. Those are referred to as a third electrode set 83. In addition, the plurality of fourth electrodes 99 are electrically connected by a fourth connection electrode. Those are referred to as a fourth electrode set 84. The electrodes of the third electrode set 83 and the fourth electrode set 84 also have a comb-like shape.
The LC barrier panel 90 maintains an opaque state when no voltage is applied. In other words, the LC barrier panel 90 is structured to be a normally black state. As illustrated in FIG. 11B, an alternating voltage is applied to only the fourth electrode set 84 on the second substrate 92. Then, the first electrode set 81 and the second electrode set 82 on the first substrate 91 are connected to the ground (GND) so that a vertical stripe transparent region is formed.
The LC barrier panel 90 is disposed on the display panel. The right image is displayed on the display pixel columns that can be seen by the right eye while the left image is displayed on the display pixel columns that can be seen by the left eye, and hence the stereoscopic image can be recognized. When this display panel is rotated by 90 degrees to be horizontal, the alternating voltage is applied to only the first electrode set 81 of the first substrate 91 while the third electrode set 83 and the fourth electrode set 84 of the second substrate 92 are connected to GND. Thus, the vertical stripe transparent region is formed similarly. On the display panel, the right image is displayed on the display pixel columns that can be seen by the right eye while the left image is displayed on the display pixel columns that can be seen by the left eye, and hence the stereoscopic image is recognized.
However, the LC barrier panel 90 described in Patent Document 1 has gaps formed between the electrodes on both the first substrate 91 and the second substrate 92. For instance, there are gaps between the first electrode set 81 and the second electrode set 82 on the first substrate 91. In addition, there are also gaps between the third electrode set 83 and the fourth electrode set 84 on the second substrate 92. Therefore, electromagnetic noise or static electricity may enter the display panel from the outside through the LC barrier panel 90 so that a malfunction or breakdown of an internal element or a thin film transistor (TFT) may occur.